Level Streaming crash when using world composition

Hey,

Our team is experiencing some pretty major crashing issues with level streaming in our open world game. We are using world composition. Our island has been split into 49 different levels in addition to other levels for caves or other things we decided to split up. We have been experiencing this crash for about a month now. Our first thought was to create a new Persistent level and see if problem would go away. This seemed to have worked for about a week or so before we started crashing again. Below is last crash log we received.

MachineId:2C2A7F424EBF4E294372EB9671AE52B3
EpicAccountId:5317144e63244d06832e99e93df21ae4

Unknown exception - code 00000001 (first/second chance not available)

Assertion failed: World->PersistentLevel [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.7\Engine\Source\Runtime\Engine\Private\LevelStreaming.cpp] [Line: 380]
Most likely caused by reference to world of unloaded level and GC setting refe

KERNELBASE + 46045 bytes
UE4Editor_Core!FOutputDeviceWindowsError::Serialize() + 292 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\windows\windowsplatformoutputdevices.cpp:95]
UE4Editor_Core!FOutputDevice::Logf__VA() + 248 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\misc\outputdevice.cpp:144]
UE4Editor_Core!FDebug::AssertFailed() + 1079 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\core\private\misc\outputdevice.cpp:224]
UE4Editor_Engine!ULevelStreaming::RequestLevel() + 860 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\levelstreaming.cpp:380]
UE4Editor_Engine!UWorld::UpdateLevelStreamingInner() + 497 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\world.cpp:2238]
UE4Editor_Engine!UWorld::UpdateLevelStreaming() + 592 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\world.cpp:2306]
UE4Editor_Engine!UGameViewportClient::Draw() + 3865 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\gameviewportclient.cpp:932]
UE4Editor_Engine!FViewport::Draw() + 1223 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\engine\private\unrealclient.cpp:995]
UE4Editor_UnrealEd!UEditorEngine::Tick() + 8339 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\editor.cpp:1515]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() + 22 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\editor\unrealed\private\unrealedengine.cpp:347]
UE4Editor!FEngineLoop::Tick() + 4179 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launchengineloop.cpp:2257]
UE4Editor!GuardedMain() + 1404 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() + 26 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() + 249 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.7\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__tmainCRTStartup() + 329 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]

Hi joshezzell,

Level Streaming does not work with World Composition, and crash is probably a result of this. Can you give me some details about how you set up your levels while World Composition was enabled? That should not have been possible. Or am I misunderstanding your setup?

Additionally, it would be helpful to see log from project when this crash occurred. You can find this in project’s Saved\Logs folder. Please and attach that here. Thanks!

Hey ,

Right, it doesn’t work with World Composition. This is what is slightly confusing about issue. Early in development we were using level streaming instead of world comp. We switched to world comp and have since deleted all level streaming volumes we created and blueprint setups for them. Could there be an issues left behind from our earlier level streaming? Maybe something we did wrong?

Hi,

Just to clarify: world composition uses level streaming, but it does not support level streaming volumes.

About crash: it caused by fact that something holding a reference to a something in sub-level package. When it crashes it should print out reference chain into log file. Could you attach one of log files here?

Didn’t have log file from that day, but ‘produced’ a new one, which is attached (along with dump files).

Looking at logs I can’t say for sure why it crashes. Looks like it happens when editor duplicates sub-level Landscape_3-4 for PIE session. Could you create an isolated project with persistent level and Landscape_3-4 and see if crashes on PIE start? We can then debug that project to find actual cause of crash.

Sorry about late response. We’ve been a bit busy with project. Josh is currently setting up that new project, but in meantime, just to give you a better perspective of our crashes, I have included an image (of a tiny area of our world) showing where crash occurs, and why I think it is unlikely that Landscape_3-4 is the (sole) culprit of our issue.

Could you temporally remove all foliage from all sub-levels and see if crash disappears?

Temporarily removing foliage seems to have fixed issue for us. We have also found that while playing in standalone window or a cooked game, it does not crash. Thus, this issue is not as critical as we first thought.

However, removing foliage is not a permanent fix, so we will continue monitoring issue.

Hi Zaldir,

We haven’t heard back from you about a test project in a while. Are you still experiencing this issue? If so, please upload test project somewhere and reply with a link so we can take a look. Thanks!

I think we dropped working on test project, when we could confirm that it was Landscape_3-4. And no, we are no longer experiencing issue. Thank your assistance in matter!